On the other hand, with the concept of "album" feeling slightly old-school, perhaps that makes it less probably that the king is ever dethroned, who knows.
There's been a great divergence in musical tastes since the 80's, probably aided by the increased availability of "niche" music that would have had too small an audience to be profitable in the past - dollars that would have gone to the #1 album are now being spread down "the long tail."
Michael Jackson's popularity also seemed to cut across racial lines and some age lines in a way that doesn't happen anymore. Can you imagine the same audience listening to Mariah Carey and Snoop Dogg? Tren Reznor's fans listening to Miley Cyrus? Jackson had a genre-crossing power.
I'd be willing to bet a large amount of money that it will never change.
..just checked the best selling albums list:
Best seller of 90s: 42 million copies
Best seller of 00s: 24 million copies
Thriller: 100+ million copies